Background: Acute Compartment Syndrome (ACS) is a limb threatening process by which increased pressure within a fascial compartment exceeds perfusion pressure, resulting in tissue ischemia. Historically, this diagnosis has been made almost entirely on clinical suspicion. Previous studies have evaluated using several laboratory markers for detecting ongoing ACS in hospitalized trauma patients. Serum creatinine kinase (CK) levels >4,000 U/L, chloride levels >104mg/dL and blood urea nitrogen (BUN) levels <10mg/dL were found to have 100% association with the diagnosis of ACS, with a sensitivity and specificity of 0.85 and 0.87 respectively (Valdez et al., 2013). To date, this strategy has not been studied in emergency department (ED) patients, which this study aims to address.
Methods: A retrospective chart review of adult patients across 12 community and 1 academic ED was performed. ED diagnosis of ACS was determined by extracting International Classification of Diseases 9 and 10 codes from the electronic medical record for encounters between February 22nd, 2008 and October 1st, 2018. Serum values were collected for each patient; CK, BMP, ionized calcium, and lactic acid. A non-matched control group comprised of patients without ACS whom had tibia and/or fibula fractures were analyzed to compare to our cohort.
Results: We identified 4,241 patients whom met our inclusion criteria: 1,243 ACS patients and 2,998 tibia/fibula fracture patients. Univariate regression modeling identified creatinine (Cr), BUN, potassium, bicarbonate (HCO3), CK, lactic acid and ionized calcium as independent predictors of ACS. In the multivariate regression model, elevated Cr and low HCO3 were significant predictors of ACS with a c-statistic of 0.77. Serum CK >4,000 U/L was found to be a significant predictor of ACS with an odds ratio of 3.515 (95%CI 2.1-5.9) with a specificity of 90.75 and sensitivity of 4.63.
Conclusion: Serum markers may aid in the diagnosis of ACS. Acidosis, elevated Cr (acute kidney injury), and elevated CK may suggest ongoing ACS however has low sensitivity in this population of ED patients.